The elderly are prone to chronic malnutrition due to a decrease in basic energy intake, reduced metabolism, an underlying disease, and the like. Even when the elderly take in sufficient energy and are given sufficient amounts of the three major nutrients and the like, they often cannot efficiently metabolize the nutrients taken in because their energy metabolic capacity has decreased. In malnutrition or a catabolic state, immunocompetence is reduced due to lowered immune cell synthesis caused by marked exhaustion or a deficiency in various nutrients, and susceptibility to infection is increased. Administration of vitamins which contribute to efficient metabolism of the three major nutrients and micronutrients involved in protein synthesis is important for improving the nutritional status and increasing the immunocompetence of the elderly and reducing their susceptibility to infection (Non-Patent document 1).    Non-Patent Document 1: FUTAMURA, Akihiko et al., Journal of Medical Technology, Vol. 48, No. 9, 2004, 3. Evaluation of Immunocompetence